HELOC Tax Deduction Rules 2026: What You Can and Can't Write Off

HELOC interest is tax-deductible — but only under specific conditions that most borrowers don't fully understand. The Tax Cuts and Jobs Act of 2017 rewrote the rules, and misreading them could cost you a legitimate deduction worth thousands of dollars annually, or expose you to an audit if you claim too much.

Here's exactly what qualifies, what doesn't, and how to keep meticulous records so you never leave money on the table.

The Core Rule: Qualified Residence Loan Interest

The IRS defines deductible home equity debt as funds used to buy, build, or substantially improve the home that secures the loan. Under IRC §163(h)(3), a HELOC is treated as "home acquisition debt" only when the proceeds are used for that purpose.

This applies regardless of what the lender calls the product. A HELOC, home equity loan, and cash-out refinance are all evaluated by the use of proceeds, not the loan type.

The $750,000 Debt Limit

For mortgages originated after December 15, 2017, the total mortgage debt eligible for interest deduction is capped at $750,000 ($375,000 for married filing separately). This cap covers all loans secured by the property combined — your primary mortgage plus any HELOC or home equity loan.

Example:

• First mortgage balance: $600,000

• HELOC used for renovation: $100,000

• Total: $700,000 → All interest is deductible

• First mortgage balance: $700,000

• HELOC used for renovation: $150,000

• Total: $850,000 → Only $750,000 / $850,000 = 88.2% of interest is deductible

Mortgages originated before December 15, 2017 use the older $1 million cap. If you have a pre-2017 mortgage, the combined limit is still $1 million for that loan, but a new HELOC added later falls under the $750,000 regime.

Qualified Home Rules

The deduction applies to interest on loans secured by your qualified home — either your primary residence or one designated second home. You can only claim a second home if it's one specific property for the tax year.

If you take a HELOC against a rental property or investment property, the interest is not deductible as home mortgage interest. However, it may be deductible as a rental property expense on Schedule E, which is a different — and potentially equally valuable — deduction.

The "Substantially Improve" Standard

The IRS does not define a minimum dollar amount for what counts as "substantial improvement," but the general guidance is that the work must add value to the property, prolong its useful life, or adapt it to a new use.

Qualifies as substantial improvement:

• Adding square footage
• Installing a new HVAC system
• Complete kitchen or bath renovation
• Building a deck, pool, or ADU
• Solar panel installation
• Replacing the roof

Does not qualify:

• Routine maintenance and repairs (painting, patching, minor fixes)
• Replacing a single broken appliance
• Landscaping that doesn't add lasting value

Gray areas exist. A full kitchen renovation qualifies; replacing one faucet does not. When in doubt, consult a CPA.

How to Document Mixed-Use HELOCs

Many homeowners use a HELOC for both home improvements and personal expenses. When you do this, you must allocate interest proportionally.

Example: You have a $100,000 HELOC. You drew $70,000 for a renovation and $30,000 to pay off student loans. Only 70% of the interest is deductible.

Best practice: use a dedicated bank account for renovation funds drawn from your HELOC so there's a clean paper trail. If you commingle personal and home improvement draws, document each draw in a spreadsheet with:

• Date of draw
• Amount
• Purpose
• Contractor invoices or receipts

The IRS can request this documentation. Lenders only track your total balance, not what you used it for.

The Standard Deduction Trade-Off

Here's what many homeowners miss: the HELOC interest deduction is only useful if you itemize deductions on Schedule A. Since the TCJA nearly doubled the standard deduction, fewer taxpayers itemize.

In 2026, the standard deduction is approximately:

• $14,600 (single filers)
• $29,200 (married filing jointly)

If your total itemized deductions — mortgage interest, property taxes (capped at $10,000 SALT), charitable contributions, and HELOC interest — don't exceed these thresholds, you'll take the standard deduction and get no additional benefit from the HELOC interest.

When the deduction matters most:

• High primary mortgage balance (e.g., $600,000+ at 7%)
• Already itemizing due to large charitable contributions
• High property taxes near the SALT cap
• HELOC balance is substantial and used 100% for improvements

State Tax Rules Vary

Many states follow federal rules but not all. California, for instance, conforms to the federal HELOC deduction rules and also has its own standard deduction thresholds. States like New York have their own mortgage interest deduction frameworks.

Always verify your state's treatment with a local tax professional — the federal deduction being unavailable doesn't automatically mean your state follows suit (or vice versa).

Form 1098 and What Your Lender Reports

At year-end, your lender sends you Form 1098 showing total mortgage interest paid. This form does not distinguish between deductible and non-deductible interest — it just shows what you paid.

It is your responsibility to determine what portion qualifies based on use of proceeds. If the IRS questions your deduction, they'll ask for documentation of how the funds were used, not just that you paid interest.

HELOCs on Investment Properties

If you own a rental property and take a HELOC against it to fund improvements to that same rental, the interest is deductible on Schedule E as a rental expense — not on Schedule A as home mortgage interest. This deduction isn't subject to the $750,000 cap because it's treated as a business expense.

This is an important distinction: HELOC interest on a rental property can be fully deductible even if you don't itemize, since Schedule E deductions reduce your rental income directly.

At HonestCasa, we work with borrowers on both primary residence HELOCs and investment property financing. Understanding the tax treatment of each helps you structure your borrowing strategy correctly from the start.

HELOC vs. Cash-Out Refinance: Tax Treatment Is Identical

Some borrowers assume a cash-out refinance has different tax treatment from a HELOC. It doesn't — the same "buy, build, or substantially improve" test applies. The deductible portion of a cash-out refi is the amount used for qualified purposes, subject to the same $750,000 cap.

Key Dates and Sunsets

The TCJA's mortgage interest rules are set to expire after 2025 unless Congress acts. If the law sunsets, the pre-2018 rules would return: $1 million cap, and home equity debt used for any purpose would be deductible again.

As of early 2026, no extension has been enacted. Congress has discussed extending many TCJA provisions, but nothing is finalized. If you're making borrowing decisions partly based on the tax deduction, talk to your CPA about the potential rule changes.

How to Maximize Your HELOC Tax Deduction

1. Use HELOC funds exclusively for home improvements — keep all renovation draws separate
2. Save every invoice, receipt, and contractor contract
3. Track draw dates and amounts in a spreadsheet linked to expenses
4. Compare itemized vs. standard deduction before filing — run the numbers both ways
5. Consult a CPA if your HELOC was used for mixed purposes or you're close to the $750,000 cap
6. Watch for TCJA sunset — tax rules may change after 2025

Bottom Line

The HELOC tax deduction is valuable but narrow. It's not a blanket perk that applies to everything you charge to your home equity line — it's specifically tied to using the money to improve the home securing the loan. Follow the rules, document everything, and work with a tax professional if your situation involves mixed-use draws or multiple properties.

If you're ready to put your home equity to work on a qualifying renovation, HonestCasa can help you compare HELOC options from multiple lenders in minutes. Get a rate estimate today at honestcasa.com.